Two alternatively spliced transcripts generated from OsMUS81, a rice homolog of yeast MUS81, are up-regulated by DNA-damaging treatments

OsMUS81, a rice homolog of the yeast MUS81 endonuclease gene, produced two alternative transcripts, OsMUS81α and OsMUS81β. OsMus81α contained a Helix-hairpin-Helix (HhH) motif at the N- and C-termini, and a conserved XPF-like motif in the center, while the OsMus81β isoform lacked the second HhH motif by alternative splicing of a cryptic intron generating a truncated protein. The two transcripts were induced after DNA-damaging treatments such as high intensity light, UV-C and γ-radiation. The yeast two-hybrid assay detected a strong interaction between OsMus81 and OsRad54 recombinational repair proteins. These findings suggest that OsMus81 functions in maintaining genome integrity through homologous recombination.